Re: Limiting query research to a specified n. of records

[Björn Steinbrink]

MySQL will stop searching for records once it has found enough to satisfy the LIMIT clause. But if you use an ORDER BY clause and there's no index that MySQL can use to retrieve the rows in the requested order, of course all rows have to be fetched first, then sorted and finally the N requested rows are sent to the client.
If that is the case for you, you'll have to add an index that helps MySQL fulfilling the ORDER BY requirement, which will again make it stop reading rows once enough are found to satisfy the LIMIT.